In modern firearms, “caliber” is the approximate inner diameter of the barrel and the corresponding diameter of the ammunition or projectile used in the firearm, measured in inches or millimeters. When the barrel diameter is given in inches, the abbreviation “caliber” is used in place of “inches.” For example, a small bore rifle with a diameter of 0.22 inch is a .22 cal. When spoken, however, the decimal point is generally dropped and is referred to as “twenty-two caliber”. Calibers of weapons can be referred to in millimeters, for examples “nine millimeter,” or abbreviated as 9 mm. Further, loaded or live ammunition is generally referred to as “cartridges,” while “casings” or “shells” generally refer to the spent ammunition cartridges.
While modern cartridges and cartridge firearms are generally referred to by caliber, they are still grouped together based on bore diameter. In small arms, such as handguns and rifles, even different caliber casings from many firearms are very close in size. Once the bullet has been fired, the generally hollow brass cylinders of the casings or shells are ejected and discarded from the firearm, and may then be recovered and reused. When the spent cartridges or casings are mixed together in large quantities, such as after sweeping up at a firing range, these mixed shells may be difficult and time consuming to sort because of their close similarities, both in appearance and diameter. However, the casings and shells must be separated by caliber before they can be cleaned, reloaded or packaged for resale. Mixed quantities of empty casings or shells must be sorted by hand, a tedious and time-consuming process.
In preparation of this application, prior art was examined. For example, U.S. Patent Application Publication US2005/0226489 discloses a machine vision system for identifying and sorting projectiles and other objects. Another reference, U.S. Patent Application Publication US2003/0057137 is directed to a cartridge sorting machine which separates live ammunition from spent cartridges.